Write the notes based on understanding from the learning content.
#Strategy Design Pattern
• Is-A relation is a inheritance only.
○ Eg: Car is a Vehicle, Bike is a Vehicle etc.
• When there are multiple child of a class and overriding the method defined in base class in same manner as that of other child class then it would led to duplicacy of code.
Eg: When child class using their own capability instead of using it's parent and other child at same level have the same as of their neighbour child then code duplication occurred and it will continue if there is multilevel hierarchy then we can't do the Code Reusability.
We will create a Drive Strategy Interface and it has 2 or n number of methods like normal_drive, special_drive, xyz_drive etc. and instead of defining drive method in Base class, we will create object of Drive Strategy Interface in Base class and now child of this Base class will call the respective method of Drive Strategy Interface.
Question Asked in Company from this in Walmart -
Ques : Implement the Notify Me button we saw in Amazon Cart once the Product comes from Out of Stock and available for customers who click on Notify me they all need to get notification for this.
Eg : Weather Station which notify mobile and television observers at regular interval with current temp.
Def : Adding(Decoarate) Additional Feature on an object which itself make another object and we can decorate that new object as well.
Use Cases
1. Pizza Shop : On a base Pizza we can decorate it by adding multiple topings like extracheese(f2), mushroom(f3), extraveggies etc.
2. Base Coffee: Let say we have Espresso coffee so we can decorate it with extra milk, cream which itself make another object and we can decorate that new object as well.
Why you need Decorator Pattern ?
Ans : To avoid Class Explosion - It refers to a situation where the number of classes in a software system grows significantly, often leading to complexity and maintenance challenges. Having indefinite permutation and combination.
Question Asked on this topic - Design Coffee Machine, Pizza Shop to calculate the cost
